public class Main {
    public static void main(String[] args) {
        Vector v1 = new Vector(2.0f, 1.0f);
        Vector v2 = new Vector(2.0f, 0.0f);

        System.out.println("v1 * 2.0 = " + v1.multiNum(2.0f));
        System.out.println("v1 · v2 = " + v1.dot(v2));
        System.out.println("v1 和 v2 夹角 = " + v1.getAngleDeg(v2));
        System.out.println("v1 对于 v2 的投影 = " + v1.getProj(v2));
    }
}
